The present disclosure relates to optical surface topology detection systems. The present disclosure also relates to surgical illumination and surgical navigation systems.
Optical illumination plays an important role during medical procedures and is especially vital in the surgical theatre, but also important in specialties such as dentistry, ophthalmology and gastroenterology. Lighting sources used in surgical environments typically need to provide bright, uniform, and shadow-free illumination with little visible temporal or spatial modulation. Light emitting diodes (LEDs) are becoming the preferred choice of illumination in medicine due to their high efficiency, long life times and relatively low cost.
Recently, 3D surface topology detection has been successfully applied to a broad range of medical applications including dentistry, orthopedics, surgery, and radiation therapy. This technique provides datasets with sub-millimeter accuracy, which can be used to position the patient for a procedure, design surgical/dental implants, and/or for registration with other imaging modalities to provide subsurface information to the practitioner.
Surface topology datasets can be generated in a number of ways, but typical systems include laser range finders, photogrammetry systems, and structured light imaging systems. For example, stereo structured light imaging can be used to generate surface topology images. This method involves active illumination of the field in order to easily identify correspondences (in images captured by a camera system) when compared to more computationally intensive approaches (such as photogrammetry). Some of the most robust and accurate structured light techniques use sequences of binary patterns, often in conjunction with sinusoidal patterns to further enhance accuracy. To obtain robust reconstructions in the presence of ambient lighting, these methods typically project the inverse binary pattern in order to correctly label pixels.
With recent advances in Digital Light Processing (DLP) technology, the projection of such patterns at very high speeds (1000's of times per second) is now possible. In addition, advances in camera and computing technology have also enabled the synchronized acquisition of these patterns at very high speeds. These recent developments make it practical to perform continuous or snapshot high-speed surface topology imaging of anatomical targets during medical procedures.
Navigation systems are often employed in the surgical theatre, to aid the surgeon performing the procedure by showing the relationship between the patient's current anatomical state and some preoperative or intraoperative images obtained from an imaging modality such as computed tomography (CT). This relationship is visually displayed to the surgeon via a computing and display unit, giving the surgeon subsurface information that they would typically lack without the navigation system.
Most navigation systems are based on optical triangulation of fiducial markers within the tracking unit's field of view. These reflective fiducial markers can be found by illuminating the field of view with a light source, for example, in the near infrared, and viewing the field with a stereo pair of near infrared cameras separated by a baseline, yielding two distinct views of the area (navigation module). Navigation systems may also rely on active fiducial markers, which use near infrared LEDs to emit light that is directly captured by the stereo pair of near infrared cameras. By attaching a plurality of these fiducial markers to a known object, the 3D position and orientation of that object can be determined.